Annealing temperature-regulated oxygen vacancy engineering in In2O3 nanorods for enhanced room-temperature NO2 sensing: Experimental investigation and DFT verification

High-performance sensors for toxic gases have been the goal of research in the industry. In this study, In 2 O 3 nanorods were grown on ceramic tubes using a hydrothermal method, and a series of gradient annealing temperatures were set to obtain different samples through annealing in air atmosphere. Among them, In 2 O 3 annealed at 400 °C (In 2 O 3 -400) showed the highest oxygen vacancies and chemical adsorbed oxygen ratio. The gas sensing performance test demonstrated that In 2 O 3 -400 exhibited excellent sensitivity to NO 2 at room temperature, its response was 4.58 at 500 ppb and 146.58 at 50 ppm. Density functional theory (DFT) analysis was used to study the adsorption mechanism of nitrogen dioxide on pure In 2 O 3 and In 2 O 3 with V O materials, showing that the existence of oxygen vacancies enhanced the adsorption capacity of In 2 O 3 for NO 2 , and the DFT calculation results were in accordance with the experimental data. This study determined the optimal annealing process conditions, providing theoretical and experimental support for the development of high-performance room-temperature In 2 O 3 -based NO 2 gas sensing devices.